While the discovery of dinosaur bones and teeth is relatively common, finding soft tissues like muscle as fossils is rare. However, an international research team has made an extraordinary find: evidence of mineralized red blood cells within a dinosaur fossil dating back 115 million years. The discovery was made in a hind leg bone belonging to an individual of the species Aratasaurus museunacionali, found in northeastern Brazil.
The researchers identified biomolecules derived from heme, a component of the protein hemoglobin responsible for oxygen transport and the red color of blood. Kliti Grice, a geochemist at Curtin University in Perth, Australia, clarified to Reuters that they did not find a vial of dinosaur blood. Instead, she described the findings as a "mineral and molecular echo of ancient biology." Grice noted that detecting intact heme-derived molecules in 115-million-year-old red blood cells is astonishing and represents a groundbreaking discovery.
This analysis enables a new form of molecular paleontology, allowing scientists to study the evolution of blood, metabolism, and activity in long-extinct animals. The study, led by Grice, was published in the journal "Proceedings" of the US National Academy of Sciences. Upon examining the vascular channels within the hind leg bone, the team found ellipsoidal microstructures approximately 20 micrometers in diameter that resembled red blood cells, or erythrocytes.
Further analysis using mass spectrometry identified the iron-containing compound heme b and the amino acid hydroxyproline, which is essential for the structural protein collagen. A comparison with microorganisms in the surrounding environment supported the interpretation that these findings were indeed red blood cells rather than contamination from the sediment layer. The team estimates the fossil belonged to an immature animal weighing approximately 32 kilograms.
The exceptional preservation is attributed to the animal being rapidly buried under an oxygen-poor layer shortly after death. Consequently, the red blood cells were mineralized through contact with the manganese oxide mineral hausmannite, protecting them over the long period. Grice stated that these findings challenge long-held assumptions that certain biomolecules like hemoglobin cannot survive significant geological timeframes.
Martin Van Kranendonk, a planetary researcher at Curtin University who was not involved in the study, suggested the implications go even further. He noted that the study demonstrates how molecular structures can remain protected against adverse conditions over long periods, which is also significant for astrobiology and the search for life in the universe.
Sources: Der Spiegel.